A TFT is a very important component as a main component of a display of a portable personal computer, a laptop personal computer, a television, or the like.
Companies manufacture TFTs by their methods. Since the process of manufacturing a TFT is complicated and various metals and metal oxides are deposited a plurality of times, simplification of the process is demanded.
In a process of manufacturing a conventional TFT array, as materials of a gate electrode and a source/drain electrode, metals such as Cr and TaW are used.
Although Cr is easily processed, there is a problem that Cr is easily corroded. Although TaW is resistive to corrosion and the like, it has a problem of high electric resistance and the like.
Consequently, a TFT array using wires made mainly of aluminum as a metal which is easily processed and has low electric resistance has been proposed.
However, when an aluminum electrode is in direct contact with a silicon layer and a drive electrode, problems occur such that aluminum is diffused into the silicon layer, thereby deteriorating device performance, and aluminum is oxidized and converted into alumina, it increases the electric resistance with the drive electrode, and the device does not operate normally.
Attempt is being made to reduce the contact resistance with the drive electrode by sandwiching the aluminum electrode by Mo or Ti.
In order to sandwich the aluminum electrode, however, a film made of Mo or Ti has to be formed first, after that, a film of a metal containing aluminum as a main component is formed, and a film made of Mo or Ti has to be formed again. Consequently, there is a drawback that the process is complicated.
On the other hand, attempt is also being made to solve the problem by using a silver or copper electrode. However, silver and copper have low adhesion to with a silicon nitride film, a silicon wafer, or the like which is made of glass or an insulating film. It causes a problem such that silver and copper come off during the manufacturing process.
An object of the invention is to provide a conductive thin film for a semiconductor device having strong adhesion to a substrate, an insulating layer, or the like, a semiconductor device that stably operates without deteriorating performance, and a method of efficiently manufacturing the film and the device.
The inventors herein have studied wholeheartedly and, as a result, found that the object can be achieved by using a conductive thin film containing Ag atoms and Mo atoms for a gate electrode and/or a source/drain electrode of a semiconductor device.